1) Field of Disclosure
This disclosure relates to the field of extinguishing or retarding fires. The present disclosure has particular applicability to a powder type fire extinguishing agent and methods of use of the fire extinguishing agent.
2) Description of Related Art
In general, foam type fire extinguishing agents have been used to extinguish fires of flammable liquids. These include hydrophilic combustible liquids such as alcohols, ketones, ethers, and the like. In addition, fire extinguishing agents can be used for combating combustion of certain other materials such as gasoline and other fuel sources. The disadvantage of most fire extinguishers for such liquid fuel fires is that the fire antagonist is required in large volume for the purpose of extinguishing a fire. This is because the fire extinguishing agent must limit the access of oxygen to the fuel source, such as by a foam barrier. Alternatively, the fire extinguishing agent must act to cool the material below the flash or combustion point.
Many different fire extinguishing compositions and fire extinguishing systems using such compositions have been developed and are available on the market. However, re-flash or auto-ignition of the hot shortening, oils or greases in Class B fires remains a serious problem. This is true, particularly, when such fires involve large commercial establishments, such as restaurants, cafeterias, mess halls, etc. The potential danger of such fires in these types of establishments is widely recognized.
Another disadvantage of certain fire extinguishing agents is that they are comprised of or contain highly toxic materials. Many fires such as flammable fuel fires and the like should be contained very rapidly to avoid water-fuel mixture run-off from the fire site.
U.S. Pat. No. 6,989,113 teaches a starch plus ammonium phosphate in liquid form. U.S. Pat. No. 3,976,580 teaches an aqueous polyacrylamide and bentonite formulation. However, these fire extinguishing materials are in liquid form, and may suffer the related problems mentioned above.
U.S. Pat. No. 5,518,638 discloses a 1-9% aqueous suspension of silica and PEG, PPG of MW 700-600,000. Another patent (U.S. Pat. No. 5,053,146) teaches a dry powder having 70-95% B2O3 and 5-30% silica. However, these patents contain no foaming agents, and are therefore not particularly applicable to class B fires.
Some compositions utilize xanthan gum. For example, U.S. Pat. No. 6,780,991 uses ammonium phosphate, xanthan gum and surfactants, of which foaming agents would be considered. However, ammonium phosphate is rather toxic, especially when burned and accordingly, may cause unwanted environmental harm when used for fire extinguishing purposes.